Semiconductor devices are manufactured in a variety of different ways and often require die-size chip assembly. One manufacturing process often associated with die-size chip assembly is a wire bonding assembly process in which semiconductor bond pads are electrically connected to landing pads formed on an external substrate. It has been found that peeling failures of semiconductor bonding pads during the wire bonding assembly process can undermine mechanical reliability in wire-bonded devices. In other words, semiconductor bond pads and associated portions of the semiconductor device can shear or rip off as the wire bond is being attached, thus leading to poor mechanical reliability of the resulting semiconductor device.
FIG. 1 illustrates a typical wire-bonded semiconductor package 100 having a semiconductor chip 102 disposed over an external package substrate 104. A plurality of bond pads 106 are formed on the semiconductor chip 102, and are electrically connected to a plurality of landing pads 108 via a plurality of wire bonds 110. A conventional wire bonding assembly process involves initially forming a bonding ball (not shown) over the bond pad 106, by metallic bond wires 110, formed of materials such as gold or copper.
During fabrication of wire-bonded semiconductor devices, underlying semiconductor layers undergo thermal and mechanical stress as a result of the processing steps (e.g. annealing) carried out on such devices. Accordingly, with each successive processing step, the material strength of the underlying layers is weakened, thus becoming less resistant to structural impact forces that can occur during latter processing steps such as the wire bonding attachment process or testing and probing. Consequently, the bond pads 106 can shear or rip off of the semiconductor chip 102 as a result of the stress exerted thereon. In some cases, portions of the semiconductor chip 102 associated with each bond pad 106 can shear or rip off, such as portions of the semiconductor chip underlying the bond pad (e.g. a dielectric layer) or portions of the semiconductor chip overlying the bond pad (e.g. a bonding ball). Thus, there exists a need to enhance the material strength of the bond pads 106 and thereby improve the structural reliability of semiconductor-packaged devices.